Hewlett Packard G4 - Stuck at "HP Proliant" screen

Good day!

I have an older Proliant system, a DL385 G4. It was running fine until a few months ago when it first refused to start up. Upon startup I am greeted with this screen while the fans run at full power. It will hang at this screen indefinitely. There's no light on the keyboard, and there's no reaction on the screen no matter what you keys you press. All lights show up as green.

Here's a list of what I've tried so far.

Tried resetting CMOS by using switch 6.

Tried unplugging the server from power for more than an hour + holding the power button to clear remaining power.

Tried disabling security by using switch 1 and 5.

Tried connecting to the server over iLO. The iLO-interface does not seem to work. It lights up, but it does not appear on the network. Also tried on an isolated network, but no DHCP request is received by the server.

Tried running with either of the two CPU's, as well as switching between the RAM sticks.

I got it working for, like, two minutes after running a CMOS reset, but after the next reboot it was back to the same old white screen. And CMOS resets done after this does not seem to help.